Effects of storage load and word frequency on pupillary responses during short-term memory

Abstract

Letter-word memory sequences differing in word frequencies and average storage loads (ASL) were presented aurally to nine Ss. Pupil diameter, measured continuously and electronically with infrared light retroreflected from the retina, increased slightly (3.5%) during loading; markedly during recall (9% to 23% with increasing ASL). Word frequency affected pupil size only at the highest ASL. Recall errors, unaffected by word frequency, increased with increasing ASL. Contrasted with recall errors, pupil dilation indicated processing at lowest ASL (9% increase), some effect of word frequency, and a greater range of effect in relation to ASL. © 1968, Psychonomic Journals. All rights reserved.